Production of solvents



July 28, 1942. .1. E. HARVEY, JR

PRODUCTION OF SOLVENTS Filed March 14, 1941 #wif/f Ffm @0f il l 'h#m9065144 r/a/v (0x/af @ma yar #Alamy @M www@ Patented July 28, 1942PRODUCTION F SOLVENTS Jacquelin E. Harvey, Jr.,.Atlanta, Ga., assignorof one-half to Southern Wood Preserving Company, East PointGa., acorporation of Georgia Application March 14, 1941, Serial No. 383,460-

Claims. (Cl. 19E-53) The present invention relates tothe production ofvaluable liquids from tars of aromatic content and fractions thereof,crude and/ or refined.

This application is a continuation in part of my application Ser. No.352,672, filed August 14, 1940, for Production of solvents, copendingherewith, as to all matter common to the two applications.

An object of the present invention is the subjection of tars of aromaticcontent and fractions thereof, crude and/or refined, to the action ofhydrogen in step-wise manner, whereby to provide solvents of increasedsolvency, said solvents being characterized, when compared to theimmediate starting material, by a fractional increment in the lowboiling range in excess of fractional increment in the higher boilingrange.

A further object of the present invention is the production of refinedsolvents of lowered corrosivity and superior solvency, thecharacteristics of which are, among other things, dependent uponhydrogen supply as hereafter explained.

Starting materials of the present process nclude tars and fractionsthereof of aromatic content characterized by Content of oxygenatedcompounds and` Sulphur, said tars being derived from coal, petroleum, orgas or gases containing carbon; as for instance coke oven tar, water gastar, gas house tar and tars of aromatic content in general; tarsproduced by cracking hydrocarbons; tars resulting from the action ofhydrogen on hydrocarbons; high boiling extractions of carbonaceoussubstances; high boiling hydrocarbons of aromatic content having olenicand/ or naphthenic content.

Starting materials of the present process also include tars of aromaticcontent from which low boiling fractions have been removed, as forinstance tars from which solvent oils have been removed. Viewed broadly,the starting materials of the present process are tars of aromaticcontent, fractions of said tar more viscous than the starting materialdue to removal of low boiling fractions from the starting material, highboiling fractions and pitches. Materials previously subjected to theaction of hydrogen are suitable starting materials.

Especially attractive as starting materials are the tars from hightemperature coke ovens which are available in large quantities at lowprices.

The present invention may be viewed broadly as a process for theproduction of refined solvents of lowered corrosivity by subjecting thestarting material in step-wise manner to the controlled action ofhydrogen whereby to produce` said solvent having enhanced solvency, andas compared to the immediate parent material, an increment of fractionsin the lower boiling range in excess of fractional increment in thehigher boiling range.

The following examples will serve to illustrate the general principleupon which the practice of the present invention is based, as well asthe processof the present invention.

The invention will be understood from the following description ofillustrative steps comprising various methods of securing the objects ofthe invention, when read in connection with the accompanying drawingwherein the figure is a diagrammatic sketch of an apparatus for carryingout a form of the process of the invention and wherein the nature of thestep carried out in each chamber and the contents thereof are indicatedby legend.

Example 1.-A sulphur bearing coal tar creosote, characterized by contentof oxygenated compounds, acoke residue in excess of 1%, a specic gravityof in the order of 1.05, and substantially 25% residue above 355 C., issubjected to the action of hydrogen at 395 C. and 200 atmospherespressure whereby to lower sulphur content thereby lowering corrosivity,at least providing for lowered corrosivity in the finished material ashereinafter explained. The material of lowered sulphur content is thenpassed through a high pressure reaction vessel while simultaneouslyflowing hydrogen therewith in the presence of molybdenum oxide catalystand a material adapted to inuence the decompositio-n of oxygenatedcompounds contained in the starting material, as for instance iodine, ata temperature of 430 C. and 300 atmospheres pressure. The time ofcontact is one hour and the ow of gas 15,000 cubic feet per barrelrefined creosote. The beneciated creosote upon inspection will be foundto have a lowered coke residue, boiling range, specific gravity,viscosity and oxygen content. Solv-ency in some of the lower fractionswill be lowered as compared to solvents extant of comparable boilingrange.

The lowering of oxygen content will flow from, among other things, theeffect of the presence of a material selected from the group consistingof halogens, halids and derivatives thereof. By the presence of saidmaterial the reaction in the hydrogen step noted is enhanced.

By the higher boiling range is meant, as an example, the upper half ofthe boiling range.

Solvents in some of the lower fractions of the beneiiciated creosotewill be reduced in quality as compared to solvents extant of comparableboiling range.

The beneciated creosote is stripped to an upper limit of 300 C. and atleast a port1on or tne low boiling fractions thereof `are passed througha high pressure reactor at 525 C. and 200 atmospheres pressure whilecontacting a molybdenum oxide catalyst. The ow of hydrogen is socontrolled as to induce a solvent having increased solvency and anincrement of fractions in the lower boiling range in excess offractional increment in the higher boiling range.

The solvent so .produced may be fractionated to provide a refinedsolvent of lowered corrosivity of any boiling range within the limits ofthe immediate parent material, as for instance:

The refined solvents may serve as substitutes for the material havingthe boiling range or ranges of the commercial solvents noted above.

In the foregoing example it will be noted that the present lprocessprovides a method for contacting the starting material with hydrogenwhereby to lower sulphur content, thereafter, contacting the material oflowered sulphur content with hydrogen whereby to produce an intermediateproduct of lowered solvency, specific gravity, boiling range, cokeresidue, and viscosity; stripping from the beneciated material a lowboiling fraction thereof and subjecting at least a portion of said lowends to the controlled action of hydrogen whereby to enhance solvencyand produce, as compared to the immediate starting material, anincrement of fractions in the lower boiling range in excess offractional increment in the higher boiling range, thus providing therefined solvent of lowered corrosivity of the present process.

Looked at in one manner the present process provides a method fortreating tars of aromatic content, and fractions thereof, with hydrogenin step-wise manner whereby to provide refined solvents of loweredcorrosivity, said solvents being characterized by increased solvency ascompared to their immediate starting material as heretofore disclosed.The step-wise action of hydrogen being further characterized byproviding hydrogen in flow that depolymerizes ring multiplicitiesthereby inducing lowered specific gravity, coke residue, boiling range,solvency and viscosity, and last, by providing hydrogen in iiow that,among other things, increases solvency.

The step-wise action of hydrogen thus provides a method for securingrefined solvents of lowered -corrosivity and superior solvency from highboiling hydrocarbons of aromatic content, said high boilerscharacterized by the presence of ring multiplicities of great ther-malsusceptibility.

Example 2,-A sulphur containing coal tar, specic gravity 1.1641, a cokeresidue in excess of 1%, and in excess of 35% boiling at 355 C., andfurther characterized by content of oxygenated compounds is subjected tothe action of hydrogen at 330 C. and 300 atmospheres pressure for such alength of time as to lower sulphur content. The coal tar of loweredsulphur content is then passed through a high pressure reaction vesselWhile simultaneously flowing hydrogen therewith at a pressure of 300atmospheres and a temperature of 410 C.; time of contact one hour,catalyst vanadium oxide and a material selected from the groupconsisting of halogens, halids, and derivatives thereof includingsubstitution and addition products thereof, and Iiow of hydrogen 15,000cubic feet per barrel feed stock. The thus treated coal tar is found tohave a lowered specific gravity, viscosity, coke residue, boiling range,and oxygen content. In some of the fractional parts of the treated `coaltar there will be lowered solvency as compared to solvents extant ofcomparable boiling range.

The beneficiated tar is then stripped to an upper limit of 360 C. andthe low ends thereof subjected to the action of flow of hydrogen at 490C. and 200 atmospheres pressure and for such a length of time as toincrease solvency and .produce an increment of fractions in the lowerboiling range in excess of fractional increment in the higher boilingrange, thus ,providing the refined solvent of the present process.

Example 3.-A high boiling fraction of coal tar characterized by sulphurcontent, and having initial boiling point of substantially 245 C. issubjected to the action of hydrogen at 375 C. and 250 atmospherespressure for such a length of time as to reduce sulphur content. Thematerial of reduced sulphur content is then passed through a highpressure reaction chamber while simultaneously flowing hydrogentherewith at a temperature of 410 C. and 300 atmospheres pressure; thecatalyst is molybdenum oxide and tin chloride and the iiow of hydrogenso controlled as to induce no substantial percentage of coke or carbonin the reaction chamber, nor to induce any substantial percentage ofchain structures that would preclude the provision of the solvent ofenhanced solvency of the present process.

Upon inspection the beneliciated coal tar fraction will be found to havea lowered specific gravity, coke residue, boiling range, viscosity andoxygen content, and, in the case of some fractional parts of thebeneflciated material, a lowered solvency as compared to solventsextant.

The benelciated material is stripped to 290 C. and the low boilingfractions thereof subjected to the action of hydrogen at 450 C. and 200atmospheres pressure; flow of hydrogen 3,000 cubic feet per barrel feedand the time so controlled as to provide an increment of low boilingfractions in excess of fractional increment in the high boiling range.The solvency of the nally processed material is in excess of theimmediate starting material. The time of the last step may be afractional minute, or more, as for instance several minutes.

The residue incidental to the stripping step may be recycled or used asan article of commerce of enhanced value, as for instance binders or thelike.

The starting material of high carbon content, as for instance coke oventar is characterized by, in its raw state, such a percentage of highmolecular complexes or polymerized products that the refined solvents ofthe present invention are not possible of manufacture therefromdirectly, but must be produced in step-wise manner, as heretoforeexplained, whereby among other things, the action of hydrogendepolymerizes said molecular complexes contained in the startingmaterial.

The depolymerized or partially depolymerized tar or fraction thereof isthen stripped of a percentage of its low ends whereby to provide the.intermediate parent material of the refined solvents of loweredcorrosivity, said rened solvents characterized, as compared to theimmediate starting material, by an increment of fractions in the lowerboiling range in excess of fractional increment in the higher boilingrange. The residue incidental to said stripping may, because of itsdepolymerized or partially depolymerized condition serves as recyclematerial to the end that conversion of the starting material in thepercentage of the material finally remaining liquid approaches volumefor volume of the starting material into the refined solvents of thepresent invention. -v

In the conversion of starting materials, partially or approaching unity,into the rened solvents of lowered corrosivity, temperatures as low as300 C. may be employed; pressures as low as 50 atmospheres may be used.However, temperatures and pressures of an increased range provide bettercommercial practice. The time element is desirably that period whichaffords commercial recoveries of the product of, and incidental to, thepresent process. Temperatures are preferred that cause no substantialamount of coking.

Gas flows are usually held in excess of 3,000 cubic feet per barrel feedtreated. In the stepwise application of hydrogen a few trials when usingany of the starting materials will determine the gas flow whencoordinated with the selected temperature and pressure conditions whicheffect said depolymerization, The gas flow in this instance may be avariable quantity because of the varying ranges of coordinatedtemperature and pressure that may be selected. When using a chosencoordination of temperature and pressure, a few trials will readilydetermine the gas ow that provides depolymerizing conditions to the endthat solvency, specific gravity, viscosity, and boiling range arelowered.

Concerning the gas flow that increases solvency and provides anincrement of lovv boiling fractions in excess of fractional increment inthe high boiling range, said gas flow is held at that point whichinduces no percentage of nally liquid chain structures that willpreclude the enhanced solvency of the present invention. For a givencoordination of temperature and pressure, the gas iiow in the lastinstance is lower than the gas flow in the preceding instance.

Using some starting materials a gas flow of 10,000-l5,000 cubic feet perbarrel feed, or higher, has proven satisfactory for depolymerizingconditions, and, a gas flow of in the order of M300-8,000 cubic feet perbarrel feed has proven satisfactory for the final hydrogen action,however, lower gas ows may be used.

Viewed broadly, the gas flow in the instance of depolymerizingconditions may be lower than 10,000 cubic feet per barrel feed, and theiiow in the last instance is held at that point that increases solvency.

In the hydrogen action that reduces sulphur content, the action ofhydrogen may be effected in an autoclave or in a continuous plant, andin the event of continuous practice, the gas flow is maintained so as toassist in sulphur reduction and the removal thereof from the reactionzone, the while inducing no substantial percentage of carbon or thelike, nor percentages of liquid chain structures that would preclude theprovision of the refined solvents of superior solvency of the presentprocess.

Example 4.-It has been discovered that when subjecting certain mixturesof rened coal tar fractions to the action of hydrogen in accordance withthe present process for the production of solvents/or fplasticizers theformerly accepted teaching that product increment, depolymerizationand/or hydrogen absorption are linear functions of the time, is notfollowed.

When subjecting a mixture of crude coal tar fractions boilingpredominantly above 250 C. or 275 C. to the action of hydrogen, researchhas disclosed that the newly induced products, depolymerization and/orhydrogen absorption are linear functions of the time. As an example,when the above mixture of crude tar fractions is subjected to the actionof hydrogen for 2, 5-, and 8- hour periods, the newly induced products,depolymerization and/or hydrogen absorption were linear functions of thetime element.

One of the preferred starting materials of the present process is amixture of refined coal tar fractions boiling predominantly above 355 or380 C. Such a starting material is conveniently the nal residueresulting from evaporating coal tar to dryness or substantial drynessand then stripping wood preservative from the distillate. This finalresidue mass of rene-d coal tar fractions is an especially suitablerefined pitch to be used as starting material of the present process.However, in contradistinction to the mixture of crude coal tar fractionsboiling predominantly above 250 or 300 C., when the aforenamed preferredstarting material is subjected to the action of hydrogen for productionof solvents and/or plasticizers, the newly induced fractions,depolymerization and/or hydrogen absorption are not, as described forVthe other mixture of crude tar fractions, linear functions of the time.A critical period of treatment by or with hydogen exists, and which ifexceeded causes loss of newly induced fractions, polymerization and/orlessened hydrogen absorption on certain fractions of the preferredstarting material under treatment.

The critical time element because of the obvious possible variations inthe characteristics of the aforenamed refined pitch cannot be spoken ofas an arbitrary gure. It can be stated, however, that if the refinedcoal tar pitch were to be subjected to the action of hydrogen for such alength of time, which for other crude coal tar fractions wouldillustrate that the newly induced fractions, depolymerization and/orhydrogen absorption were linear functions of the time element, loss ofinduced products, polymerization and/or lessening of hydrogen absorptionwould occur. When treating the refined pitch by or with hydrogen, thecritical time element is in the order of about three hours.

In the disclosures made herein and in the appended claims distillateremoval of low boiling portions from the beneficiated material isconsidered the equivalent of fractional removal by gas movement, solventaction or the like. The converse also obtains.

A sulfur bearing refined coal tar pitch chosen from the group boilingpredominantly above, and above, 355 C., characterized by content ofoxygenated compounds, coke residue in excess of 2% and a specificgravity greater than l is subjected to the action of hydrogen at 385 C.and 200 atmospheres pressure whereby to lower sulfur content therebylowering corrosivity, at least providing for lowered corrosivity in thefinished product as hereinafter explained. The sulfur reducing hydrogenaction is so controlled as to induce no substantial percentage of low.boiling fractions, as for instance those lowl boiling fractions whoseranges are disclosed elsewhere herein. The material of lowered sulfurcontent is then passed in liquid phase through a high pressure reactionvessel while simultaneously flowing hydrogen therewith in the presenceof an oxide catalyst chosen from the group comprising the sixth andeighth periodic groups, and additional catalytic material adapted toinfluence the decomposition of oxygenated compounds contained in thestarting material, at a temperature of 435 C. and 400 atmospherespressure. The time of contact is two hours and the flow of gas 15,000cubic feet per barrel material treated. The beneficiated refined pitchupon inspection will be found to have a lowered coke residue, boilingrange, specific gravity, viscosity and oxygen content. Solvency in someof the lower fractions will be a reduced quantity as compared to thesolvency of solvents extant of comparable boiling range.

The beneciated refined pitch is stripped to an upper limit of 290 C. andthe low boiling portion thereof is passed through a high pressurereactor with a flow of hydrogen at a temperature of 515 C. and 200atmospheres pressure and for such a length of time as to increasesolvency and produce an increment of fractions in the low boiling rangein excess of fractional increment in the high boiling range, thusproviding the refined solvent of superior solvency of the presentprocess.

The residue resulting from the provision of the intermediate startingmaterial may be recycled if desired for further solvent production. Theresidue is of a more liquid nature than a comparable cut on the startingmaterial indicating that the high boiling ends which may be described asinclu-ding multiplicity of ring structures has been, at least, eithersaturated or partially saturated, thus providing the initial step in thestepwise conversion of substantially the entirety of the refined pitchremaining liquid under process conditions into the refined solvents oflowered corrosivity of the present process.

In the instance of the immediate apparent material recovered to an upperlimit of 290 C., as above described, the iinal solvent may be divided toprovide solvents of various boiling ranges as may be dictated bynecessity. When providing the intermediate starting material of thepresent process, and in the event such provision is made by taking adeep cut on the beneficiated refined pitch, the deep cut after furtherhydrogen action, as heretofore described, may provide high boilingfractions having plasticizing properties.

When subjecting a rened coal tar pitch to the action of hydrogen for theproduction of solvents in accordance with the present process, thehydrogen action characterized by solvency lowering is controllably heldat or below the critical time period, and if such is exceeded adversereactions will occur. As an example, if the critical time period isexceeded, instead of fractional increment, depolymerization and/orhydrogen absorption being linear functions of the time element, thereverse will obtain. In other words, if the critical time period isexceeded, fractional increment, depolymerization and/or hydrogenabsorption will not be linear functions of the time element, it havingbeen found, among other things, that a period in excess of that which iscritical will provide for loss of fractional increment and/orpolymerization.

As stated above the critical time element in the instance of treatingthe refined pitch with hydrogen is in the order of about three hours,and the present process is predicated on the employment of the critical,and at times less than the critical, time element.

The refined so-lvents of lowered corrosivity as iiowing from theconversion product of the refined pitch are of superior quality and arecharacterized by a preponderance of ring structures.

By the term beneciated as used herein and in the appended claims ismeant the starting material at least once subjected to the action ofhydrogen in accordance with the present process.

After the starting material has been subjected to depolymerizing action,the stripping step may be effected at any point selected within a widerange to provide a cut capable of providing, after further processing,substitutes for the boiling range or ranges of benzol, toluol, xylol,the various naphthas, and the various plasticizers.

Thus, the depolymerized starting material may be cut according to theneed at hand, said cut then being subjected to the action of hydrogenthat increases solvency as hereto-fore explained.

In the step that effects depolymerization of the high molecularcomplexes contained in the starting material, the inclusion of acatalyst adapted to influence the decomposition of oxygenated compoundscontained therein, enhances said depolymerization and allows thereduction of specic gravity, viscosity, and coke residue to proceed atan enhanced rate.

The catalysts of the present process are oxides anda material adapted toinfluence aforesaid decomposition of oxygenated compounds, said materialbeing selected from the group consisting of halogens, halids andderivatives thereof including substitution and addition productsthereof. Catalysts may be employed in any effective form as for instanceas pellets, comminuted, or supported on carriers.

If desired, comminuted catalyst may be used in the hydrogen stepcharacterized by depolymerization, and in the step characterized bysolvency increase, a rigid catalyst may be used.

By multiplicity of rings, high molecular complexes and polymerizedproducts are meant high boiling fractions of aromatic content a portionof which at least may be viewed as ring multiples: or, said terms, anyor all, may be used to describe high boiling fractions of the startingmaterial especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting materials to theprocess of the present invention, it may be desirable prior to thedepolymerizing step, or the sulphur reducing step, to at least partiallydepolymerize the molecular complexes by use of a solvent. Said solventmay be added in a small amount, or up to Volume for volume or more.Refractory solvents may be desirable, but others more susceptible to thereaction conditions inherent in and to the present process are usable.

Concerning solvents, it may be said that tar itself, as for instance,high temperature coke oven tar is constituted of high molecularcomplexes dissolved, cut back, or depolymerized with a solvent, saidsolvent being the lower boiling fractions of said tar.

The action of hydrogen may be eifected in one or more cycles orchambers, with or without releasing the pressure and with or withoutvariation of process controls.

Various modes of practicing the present invention are possible, as forinstance the depolymerzed starting material may be stripped by gasmovement; the low ends thus stripped may then, with or without releasingpressure, be subjected to further action of hydrogen. Or, the desiredstripped material may be obtained by partial release of pressure whichwould correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single reactionchamber, a series thereof, a parallelism thereof, including amultiplicity thereof.

The refined solvent of the present invention may be fractioned toprovide solvents and/or plasticizers of various boiling ranges, and inthe instance where solvents are processed from a deep cut on thedepolymerized material, the highest boiling fractions thereof or othersmay serve as a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulphur content, saidreduction of sulphur may be accomplished in the presence of a catalyst.Catalysts effective in the presence of hydrogen are usable, as forinstance the oxides and/or suldes of molybdenum, vanadium, uranium,cobalt, tin, manganese, tungsten, or the like.

In the disclosure herein made the removing of low boiling fractions bygas movement or pressure release is considered the equivalent ofdistillation.

When reference is made to high molecular complexes contained in thestarting material, and when the starting material contains low boilingfractions that are not considered high molecular complexes, it is ofcourse obvious that the high molecular complexes contained in thestarting material are to a certain extent depolymerized by the solventpresent.

It will be seen that by reduction of sulphur content of the materialunder treatment during any stage of hydrogen action, the oxide catalystused during subsequent stages is at least partially protected from theeffect of the sulphur.

The decomposition influencer which it is desired to have present in thereaction zone is generally taken between 0.1 and 4 or 5 percent, basedon the feed stock, and is preferably taken between 0.1 and 1.5 percent.

Halogens, halids and derivatives thereof are employed for catalyticpurposes noted in the foregoing; however, also may be employedsubstances furnishing under the process conditions a halogen or ahydrogen halid. Ammonium chloride may be employed, also halogencompounds of coal tar oils, or the like as for instance the iodides orbromides. Also may be employed acids such as nitric, sulphuric,sulphonic, formic and acetic.

The addition of the decomposition influencer may be made prior to theentry of the feed stock into the reaction chamber, or at any suitabletime, as for instance after the charging stock has been heated,

Equivalent amounts of compounds furnishing halogen or hydrogen halid maybe employed.

The evaluation of solvent power is conveniently accomplished by ndingthe well-konwn aniline point of Kauri-butanol number. The evaluation ofplasticizing properties is conveniently accomplished by recourse tomethods suggested in chapter VI, The technology of solvents, by Dr. OttoJordon, Mannheim, Germany, translated by Alen D. Whitehead, ChemicalPublishing Company of New York, Inc., New York, New York.

Minor changes may be made in the foregoing without departing from thespirit of the invention.

I claim:

1. In the production of a solvent from the sulfur containing refinedpitch produced by stripping high temperature coal tar to at least aboutsubstantial dryness, and fractionating the overhead material to recovera liquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction to the action of hydrogen at atemperature and pressure of at least about 375 C. and 50 atmospheres,respectively, and for such a time as to lower sulfur content, whilstprecluding substantial low boiling fractional increment; subjecting thematerial of lowered sulfur content to the action of a relatively highflow of hydrogen at a temperature and pressure in excess of about 400 C.and 50 atmospheres, respectively, in the presence of an oxide catalystand a material selected from the group consisting of halogens, halidsand derivatives thereof for a period not in excess of about three hours,whereby to avoid loss of newly induced fractions; stripping newlyinduced fractions from the beneciated material; and subjecting at leasta portion of said stripped fractions to the action of a relatively lowow of hydrogen at a pressure of at least 50 atmospheres and atemperature chosen between 45o-525 C. to provide an increment offractions in the lower boiling range in excess of fractional incrementin the higher boiling range, to produce a solvent.

2. In the production of a solvent from the sulfur containing refinedpitch produced by stripping high temperature coal tar to at least aboutsubstantial dryness, and fractionating the overhead material to recovera liquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction to the action of hydrogenwhereby to lower sulfur content, Whilst precluding substantial lowboiling fractional increment; subjecting the material of lowered sulfurcontent to the action of a relatively high flow of hydrogen in thepresence of an oxide Catalyst and a material selected from the groupconsisting of halogens, halids and derivatives thereof for a period notin excess of about three hours, whereby to avoid loss of newly inducedfractions; stripping newly induced fractions from the beneciatedmaterial; subjecting at least a portion of said stripped fractions tothe action of a relatively low flow of hydrogen to provide an incrementof fractions in the lower boiling range in excess of fractionalincrement in the higher boiling range; and fractionating the last namedbeneficiated material to segregate a solvent.

3. In the production of a solvent from the sulfur containing refinedpitch produced by stripping high temperature coal tar to at least aboutsubstantial dryness, and fractionating the overhead material to recovera liquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction to the action of hydrogenwhereby to lower sulfur content, whilst precluding substantial lowboiling fractional increment; subjecting the material of lowered sulfurcontent to the action of a relatively high flow of hydrogen in thepresence of an oxide catalyst and a material selected from the groupconsisting of halogens,

halids and derivatives thereof for a period not in excess of about threehours, whereby to avoid loss of newly induced fractions; stripping newlyinduced fractions from the beneficiated material; subjecting at least aportion of said stripped fractions to the action of a relatively lowflow of hydrogen to provide an increment of fractions in the lowerboiling range in excess of fractional increment in the higher boilingrange and fractionating the last named beneciated material to provide asolvent boiling predominantly between 100 C. and 150 `C.

4. In the production of a solvent from the sulfur containing rened pitchproduced by stripping high temperature coal tar to at least aboutsubstantial dryness, and fractionating the overhead material to recovera liquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction to the action of hydrogen at atemperature and pressure of at least about 375 C. and 50 atmospheres,respectively, and for such a time as to lower sulfur content, whilstprecluding substantial low boiling fractional increment; sub jecting thematerial of lowered sulfur content to the action of a relatively high owof hydrogen in the presence of an oxide catalyst and a material selectedfrom the group consisting of halogens, halids and derivatives thereof ata pressure in excess of about 50 atmospheres and a temperature in excessof about 400 C. for a period not in excess of about three hours, wherebyto avoid polymerization; stripping newly induced kfractions from thebeneficiated material; and subjecting at least a portion of saidstripped fractions to the action of a relatively low ow of hydrogen at apressure of at least 50 atmospheres and a temperature chosen between450-525 C. to provide an increment of fractions in the lower boilingrange in excess of fractional increment in the higher boiling range, toproduce a solvent.

5. In the production of a solvent from the sulfur containing refinedpitch produced by stripping high temperature coal tar to at least aboutsubstantial dryness, and fractionating the overhead material to recovera liquid useful as a wood preservative, and a higher boiling fractionboiling predominantly above 355 C., the process which comprises:subjecting said higher boiling fraction to the action of hydrogen at atemperature and pressure of at least about 375 C. and 50 atmospheres,respectively, and for such a time as to lower sulfur content, whilstprecluding substantial low boiling fractional increment; subjecting thematerial of lowered sulfur content to the action of a relatively highflow of hydrogen in the presence of a material selected from the groupVconsisting of halogens, halids and derivatives thereof at a temperatureand pressure in excess of about 400 C. and about 50 atmospheres,respectively, for a period not in excess of about three hours, wherebyto avoid lowered hydrogen absorption; stripping newly induced fractionsfrom the beneficiated material; and subjecting at least a portion ofsaid stripped fractions to the action of a relatively low flow ofhydrogen at a pressure of at least 50 atmospheres and a temperaturechosen between 450-525 C. to provide an increment of fractions in thelower boiling range in excess of fractional increment in the higherboiling range, to produce a solvent.

JACQUELIN E. HARVEY, YJR.

